Inspection and maintenance operations are among the most important cost contributors to the ongoing operation expenditure of offshore structures. The costs involved in the performance of these operations may be itemised as follows: labour; access; materials; and equipment. Labour is conventionally required to set up scaffolding and to carry out associated rigging work where existing access is not provided. When an access problem is to be resolved in an environment in which work maybe heavily affected by weather conditions--for example, work performed under the sea deck of an offshore platform, on piles supporting wharves and jetties and the like--then costs associated with access work may well become the top cost contributor and, in some cases at least, affect both the work schedule and the estimated budget of a project.
Heretobefore, conventional demountable scaffolding has largely been employed as the primary means for providing access to offshore structures for the carrying-out of work at locations at which cranes and derricks cannot be employed. Scaffolding is, however, a time consuming and difficult task, requiring licensed scaffolders for the undertaking. For certain inspection procedures, scaffolding may well take up to as much as 95% of total working time.